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EP-4424589-B1 - AIRCRAFT DRAIN MAST

EP4424589B1EP 4424589 B1EP4424589 B1EP 4424589B1EP-4424589-B1

Inventors

  • SCHRECK, TOBIAS
  • NAPP, CHRISTIAN

Dates

Publication Date
20260506
Application Date
20230228

Claims (7)

  1. An aircraft drain mast (401) configured to be attached to a skin portion (107) of an aircraft (100) comprising: a main body (403) bounded by a root portion (405), a front portion (407), a rear portion (409), and a tip portion (411), wherein the main body (403) comprises one or more internal conduits (415A, 415B) extending between the root portion (405) and one or more corresponding apertures (417A, 417B) located at the tip portion (411), wherein a leading edge (406) of the front portion (407) is defined by a first curve section (419) extending between a first end point (421) at the root portion (405) and a second end point (423) the tip portion (411), wherein a trailing edge (408) of the rear portion (409) is defined by a second curve section (425) extending between a third end point (427) at the root portion (405) and a fourth end point (429) at the tip portion (411), wherein the first curve section (419) or the second curve section (425) comprises an inflection point (435, 437) adjacent to the root portion (405), and wherein the second curve section (425) has a curvature that is constant or increasing monotonically from the third end point (427) until a point of maximum curvature is reached at an apex (431) between the root portion (405) and the tip portion (411), after which the curvature of the second curve section (425) decreases monotonically between the apex (431) and the fourth end point (429) at the tip portion (411), wherein the curve section for assessing the monotonic curving nature of the first curve section (419) or second curve section (425) starts at the inflection point (435, 437).
  2. The aircraft drain mast (401) according to claim 1, wherein a leading edge of the front portion (407) is defined by a first curve section (419) having a curvature that decreases monotonically from the first end point (421) to the second end point (423).
  3. The aircraft drain mast (401) of any preceding claim, comprising a blend or fillet edge (428) adjacent to the root portion (405).
  4. The aircraft drain mast (401) of claim 3, wherein the blend or fillet edge (428) extends around a circumferential edge (439) of the root portion (405).
  5. The aircraft drain mast (401) of any preceding claim wherein the aerodynamic main body (403) is swept at an angle α greater than 15 degrees, preferably between 30 degrees and 45 degrees, wherein the angle is the included angle between the skin portion (107) and a line formed by a point (421) and a point (433) as measured in a side projection on the ZX plane of the drain mast (401).
  6. An aircraft engine nacelle (105) or fuselage structure (103) comprising an aircraft drain mast (101, 401) according to any preceding claim.
  7. An aircraft (100) comprising an aircraft drain mast (101, 401) according to any preceding claims 1 to 5.

Description

TECHNICAL FIELD The present disclosure relates to aircraft drain masts, in particular to an improved aircraft drain mast. BACKGROUND A drain mast is a type of aircraft system component fitting. Figure 1 shows an aircraft (100) with a plurality of aircraft drain masts (101) according to the prior art that are attached in various positions to the lower fuselage (103) and engine nacelle (105) of an aircraft (100). Figure 2 shows a combined side projection view and section view of an example prior art drain mast (101) which includes a section view of the attachment to the aircraft fuselage (or nacelle) skin (107). Figure 3 shows a top view of the attachment surface (207) of the drain mast (101) in proximity or contact with the skin (107). The primary purpose of aircraft drain masts including the prior art drain mast (101) is to provide a necessary point of egress from the aircraft (100) for unnecessary fluid originating from one or more aircraft systems, or as a necessary point of ingress of air via a set of one or more vent lines or conduits (219) for one or more aircraft systems. The unnecessary fluid may originate from one or any number of fluid emitting systems, such as condensers, lubrication systems, expansion reservoirs, etc., within the aircraft (100). In figures 2 and 3, the prior art drain mast (101) projects radially outwards at an angle away from the horizontal XY plane of the aircraft (100) and extends outwards towards a narrower tip end (209) that tapers aft in the X direction to become orientated in the freestream direction (A). It should be noted that typically the freestream direction A is approximately co-linear with the airplane x axis when the aircraft is in steady and level flight. In a typical coordinate convention appreciated by the skilled person, the X, Y and Z axes correspond to a set of orthogonal aircraft axes, whereby X is the longitudinal aircraft axis, Y corresponds to the lateral aircraft axis oriented in a spanwise direction of the wing of the aircraft, and the direction Z corresponds to the vertical axis, these three directions being orthogonal to each other, and create a set of three orthogonal planes with respect to each other. An aircraft drain mast (101) typically comprises an oblong and symmetrically shaped main body (203) that projects outward from the aircraft skin (107), as mentioned, when it is installed to the aircraft (100). The tip portion (209) of the drain mast (101) comprises a planar aft facing surface (204) with one or more aft-facing apertures (221) (i.e. facing in the A direction as shown in figure 1) that are the termination point of the corresponding vent lines or conduits (219) that are enclosed by the main body (203) of the drain mast (101). The apertures (221) serve as the point of fluid egress or ingress from the drain mast (101). The placement and orientation of the apertures (221) at the tip (209) is an important design requirement for drain masts (101) because the apertures (221) need to be positioned at a distance from the skin surface (107) of the aircraft (100) where the airstream is steady and not turbulent. Placing the apertures (221) too close the aircraft skin (107) in areas where turbulent flow is expected (for example in the boundary layer which surrounds the aircraft (100) in flight) is problematic for fluid egress because turbulent airflow closer to the aircraft skin (107) increases the likelihood of egressed fluid to dispersed towards the aircraft and to contact the outer skin surface (107) in proximity to and /or downstream of the aircraft drain mast (101) during flight. This creates an aesthetic and operational issue for some aircraft operators. Placement of the apertures (221) in areas of steady flow is also desired in cases where fluid egress or ingress requires a steady rather than unsteady fluid pressure, which is often the case where the drain mast (101) has one or more of the vent lines or conduits (219). The main body (203) of the drain mast (100) typically attaches at a root end portion (205) (base portion or "foot") to the aircraft skin (107) at an attachment surface (207) that has an attachment surface area or "footprint" (301) (seen as the shaded area of the horizontal XY plane of figure 3. The example prior art drain mast (101) of figures 2 and 3 is fastened at a root portion using a plurality of fasteners (211) to the aircraft structure, which comprises of the skin portion (107) and a corresponding system fitting (213) located on the opposite interior side of the skin portion (107) to the drain mast (101). The main body (203) is bounded by a front portion (215), rear portion (217), root portion (205) and tip portion (209). The vent lines and conduits (219) are configured to either route through or fluidly connect to corresponding system conduit fittings (213). A disadvantage of the prior art drain mast (101) described thus far with the support of figure 2 and 3, is that the aerodynamic shape is not optimized for low drag an